Alternating-current meter.



110.848.923- PATBNTED APR.2,1907.I

w. H. PRATT.

ALTBRNATING CURRENT METER. APPHOATIOI rmzn JULY :5. 190a.

Witnesses: Inventor X? William H.Pr-at:b, %Z I y I UNITE STATESPATENTorinon 1 WILLIAM H. PRATT, 0F LYNN, MASSACHUSETTS, ASSIGNOR To GENERALELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ALTERNATlNG -CURRENT METER.

To all whom itma/y concern.-

Be it knownthat I, WILLIAM H. PRATT, a citizen of the United States,residing at Lynn, county of Essex, State of Massachusetts, have inventedcertain new and useful Improvements in Alternating-Current Meters, ofwhich the following is a specification.

My invention relates to alternating-current meters of the type in whichthetor ue is produced by coactingiarmature and fiel currents. In such'ameter in order to secure accurate measurement of the energy in a circuitit is essential that the currents in the armature and field circuitsshould be in phase when the load on the circuit in which the energy isto be measured is non-inductive. In motor-meters of the commutator typein which the armature-circuit is used as the potential-circuit it ispossible to make the selfinduction of the armature-circuit so small thatthe potential circuit is substantially non-inductive. tersuch, forinstance, as mercury-meters it is sometimes desirable to employ thefieldcircuit for the potential-circuit. In such a case the field-circuitis highly inductive, so that it is impossible to make thepotentialcirouit non-inductive except by using condensers, which areexpensive.

My invention consists in allowing the current in the potential-circuitto lag and providing phase-controlling devices in the series circuitadapted to lag the current in the series circuit of the meter behind thecurrent in the load-circuit by an amount e ual to the lag in thepotential-circuit. In t 's manner the currents in the series andpotential circuits of the meter are brought into phase when the currentin the load-circuit is in phase with the or, in other wor s, when theload is non-inductive. One convenient method of lagging the current inthe series circuit of the meter consists in placing a reactance inseries with the series circuit and shunting both the reactance and themeter with a non-inductive resistance.

My invention will best be understood by reference to the accompanyingdrawing, which shows diagrammatlcally an alternating-current meter withits circuit arranged in accordance with my invention.

Specification of Letters Eatent. 4 Application filed July 26; 19cc.Serial No. 827,698.

In certain types of me-' gotential in the load-circuit I IPatent edApril 2, 1907.

In the drawing I have shown my invention applied to a meter of thegeneral construction shown in Patent No. 7 91 ,673, issued to F. P. CoxJune 6, 1905; but it will be under-.

stood that my invention is in no way limited to this particular type ofmeter.

In the drawing, A re resents a source of alternating current supp yingthe translating devices B.

O 0 represent the field-magnets of themeter, the coils of which areconnected in series with each other and in shunt to the load-circuit. iY

A non-inductive resistance D is inserted in series with the field-coilsto reduce the lag of.

the current. g

E represents'a casing containing a conducting fluid F, such as mercury.

c K represents a contact entering the casing L represents a drag-magnetfor retarding the movement of the diskb It will be seen that the ma etsC C possess considerable reactance, so t at even with a non-inductiveresistance in series the current in the potential-circuit will lag aconsiderable amount behind the potential of the load-circuit. In orderto prevent an error in the registration of the meter from this cause, I

provide a reactance M in series with the series circuit of the meter andconnect in shunt to the reactance and metera non-inductive resistance N.With this arrangement the current passing through the armature-circuitof the meter lags behind the current in the load-circuit, and byproperly adjusting the reactance M and resistance N the same phase G.represents a conducting-disk sub-- ticular construction and. arrangementof parts here shown, but aim in the ayemied claims to cover allmodifications w h are within the scope of my invention.

What I claim as new, and desire. to secure by Letters Patent oi theUnited States, is

i- In-an aitematingmunent meter, an imciuctive potential-circuit, aseries: circuit anfl phase-controlhng means in saii series circuitadapted to bring the current in the series circuit of the meter intophase with the current in the ntentiat-eirmrit on non-imtuctive load.

2- In an alternating-current meter, in combination with a. lent-circuit,the energy in which is to be measureti, an inductive potential-circuit,a series clrcuit, and phase-retaniing means ads ted to lag the currentin said. series circuit hind the current in the load-circuit by anamount equal te the at the current in the petential-eiseuit bmnd thepotential oi the toeri-eineuit.

3n In an alternating-current meter, animrluctive potentialwircuit, a.series circuit, an

inductive resistance in the series eireuitin sea iases.

lies with the meter, a resistance oi smaner self-induction in shunt tsthe firstmentionedl resistance and meter.

in an alternating-current meter, an

l (inetive potentialwirmxit a sedan circuit, a

v the meter reactance in the series circuit in series with M a.non-mriuctlve resistance shunting tlie reactance and! meter.

5. in an alternating-current meter, in combination with a loacl-circuit,the energy in which is to be measured, a field-circuit in shunt to theload circuit, an armature-circuit in series with the load-circuit, andphaseretarciing means in the armatmre cirenit adantedi to lag thearmature-armrest the oafi-cm'rent by an amount. equal ta lag oi thecurrent in the the potential in the ionn-einmit- 6. In analternating-current meter, combination with a least-circuit, the energyv in which is to be measured], a fieln wirenlt shunt to theloan-circuit, an SIIBEtHI'Hil-Q-Eit" in series with the loan-circuit, areactance series with the armatureecircuit, and; a non? inductiveresistance in shunt t0 the andl armstme mm.

in whereas? 1 herennte this 20th (lisy Hi My, recs- WILLIAM H.

t my hast Jenn A Memrntns 5.1L, Emmi Q. Wns'rmw W2;

